Circuits.dk Something about electronics circuits

In battery-operated devices that have removable batteries, you usually need to prevent the batteries being connected the wrong way to prevent damage to the electronics, ....

In this article we will make a simple datalogger application running on the Raspberry Pi. It is compatible with Raspberry Pi Zero W, Pi 2 and Pi 3.

So, what is Bash? The terminal (or ‘command-line’) on a computer allows a user a great deal of control over their system. All of these tools allow a user to directly manipulate their system through the use of commands. These commands can be chained together and/or combined together into complex scripts (see the linux usage page on scripting) that can …

What is Claws mail? Claws Mail is an email client aiming at being fast, easy-to-use and powerful. It is mostly desktop-independent, but tries to integrate with your desktop as best as possible. The Claws Mail developers try hard to keep it lightweight, so that it should be usable on low-end computers without much memory or CPU power, which is great …

InfluxDB is an easy to use open-source time series database developed by InfluxData. It is written in Go and optimized for fast, high-availability storage and retrieval of time series data in fields such as operations monitoring, application metrics, Internet of Things sensor data, and real-time analytics. It also has support for processing data from Graphite. A time series database have …

Super capacitor discharge time calculator. This calculator determines timekeeping operation using a supercapacitor (ultracap) based upon starting and ending capacitor voltages, discharge current, and capacitor size. Formulas used: Bt(seconds) = [C(Vcapmax – Vcapmin)/Imax]  This formula is valid for constant current only. Bt(seconds) = -log(Vcapmin/Vcapmax)(RC) = t  This formula is valid for linear current only (simple resistive load). Edit the input …

The formula used in this calculation is from the famous Harold A. Wheelers approximations which is accurate to <1% if the cross section is near square shaped. $$L(\mu H)=\frac{31.6*N^2*r1^2}{(6*r1+9*L+10*(r2-r1))}$$ where… Please note that the diameter is measured from center of wire trough center of the coil and to center of the wire on the opposite side. Inductance (L): uHmHH Coil …

Winding the wire in a single layer produces an inductor with minimal parasitic capacitance, and hence gives the highest possible self-resonant frequency (SRF). Striving to obtain a high SRF and low losses is the key to producing coils which have radio-frequency properties bearing some useful resemblance to pure inductance. The calculation is based on Harold A. Wheeler’s 1928 formula for …

This is an popular coil geometri used in todays wireless charger circuits. The formula used in this calculation is based on the Harold A. Wheeler approximations for air core flat spiral coil inductor. …where: 1 inch = 0,0254m=2,54cm = 25,4mm. This formula applies at ‘low’ frequencies (<30MHz) using enameled copper wire. Some people call it “magnet wire”. Click on image …

The first approximation is based on a modification of an expression developed by Wheeler; the second is derived from electromagnetic principles by approximating the sides of the spirals as current-sheets; and the third is a monomial expression derived from fitting to a large database of inductors (and the exact inductance values). All three expressions are accurate, with typical errors of …